Report says Asian carp could reach all 5 Great Lakes in 20 years
A silver carp, a variety of the invasive group of Asian carp, is held by a scientist after being pulled from the Illinois River near Havana, Ill., on March 28, 2012. (Chris Walker, Chicago Tribune / July 12, 2012)
Carp experts have long debated whether the feared fish, which have been found in the Illinois River, would be able to flourish in the Lakes.
Previous studies have cast doubts, noting potential food shortages and relatively cold water temperatures.
But the study led by the Department of Fisheries and Oceans Canada, which included two U.S. Geological Survey scientists, found that there would be enough food to feed the fish, especially in Green Bay, Saginaw Bay, Lake St. Clair and Lake Erie.
Water temperatures would also not be too cold to stymie survival, according to the report.
“The questions everyone has been asking are: ‘Can a breeding population survive in the Great Lakes and would it be a significant problem if they did?'” USGS Director Marcia McNutt said in a released statement. “Now we know the answers and unfortunately they are ‘yes and yes.’”
The Binational Ecological Risk Assessment included Great Lakes researchers, managers and decision-makers and relied on prevention measures underway through November 2010.
The report found that when compared to Asian carp's native range, the Great Lakes have similar characteristics.
The authors noted that at least three Asian carp were captured in Lake Erie more than 10 years ago and appeared healthy, indicating they were “surviving and growing very well.” But none has been found since then.
Modeling done for the report also showed that it would only take an adult population of 10 females and 10 males to have a greater than 50 percent chance of successfully spawning.
The study's authors estimated that following entry, the fish would spread throughout the Great Lakes within 20 years, decreasing plankton and leading to declines in native fish species, including some that are commercially and recreationally important.
Lakes Michigan, Huron and Erie face the greatest risk relative to the other lakes, according to the report.
The most likely pathway was determined to be through the Chicago Area Waterways System.
The report comes as the Asian Carp Regional Coordinating Committee has begun intensive monitoring in Lake Calumet and surrounding areas after taking multiple samples that tested positive for carp DNA.
The effort began on Tuesday and included netting and electrofishing. No Asian carp had been found as of Thursday afternoon. The rapid response will continue through Friday.
Authorities have said that the presence of carp DNA does not necessarily indicate live fish in the area. An Asian carp was captured in Lake Calumet in 2010.
But Thomas Cmar, an attorney in the Midwest office of the Natural Resources Defense Council, said the report was troubling in light of the recent positive results for environmental DNA, or eDNA.
“Today's study by the Canadian government makes it clear that the threat is much more dire (than has previously been stated),” Cmar said. “There is no time to waste.”
A transportation bill signed by President Barack Obama this month directed the Army Corps of Engineers to expedite a massive study that is under way to find a permanent solution to the Asian carp problem.
The Obama administration has invested more than $150 million to fight Asian carp. Ongoing efforts include electric barriers in the Chicago Area Waterway System near Lockport.
Scientists also are working on other control methods that would include the use of pheromones to attract the fish and toxins to kill them.
But some environmental groups have long argued that such measures are costly and may ultimately be flawed and ineffective.